/*
 * Copyright 1999-2011 Alibaba Group Holding Ltd.
 *
 * Licensed under the Apache License, Version 2.0 (the "License");
 * you may not use this file except in compliance with the License.
 * You may obtain a copy of the License at
 *
 *      http://www.apache.org/licenses/LICENSE-2.0
 *
 * Unless required by applicable law or agreed to in writing, software
 * distributed under the License is distributed on an "AS IS" BASIS,
 * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
 * See the License for the specific language governing permissions and
 * limitations under the License.
 */
package com.alibaba.druid.util;

import java.io.ByteArrayOutputStream;
import java.io.IOException;
import java.io.InputStream;
import java.io.InputStreamReader;
import java.io.OutputStream;
import java.io.PrintWriter;
import java.io.Reader;
import java.io.StringWriter;
import java.io.UnsupportedEncodingException;
import java.lang.management.ManagementFactory;
import java.security.MessageDigest;
import java.security.NoSuchAlgorithmException;
import java.text.SimpleDateFormat;
import java.util.Date;
import java.util.Properties;

import javax.servlet.GenericServlet;

public class Utils {

	public final static int DEFAULT_BUFFER_SIZE = 1024 * 4;

	public static String read(InputStream in) {
		InputStreamReader reader;
		try {
			reader = new InputStreamReader(in, "UTF-8");
		} catch (UnsupportedEncodingException e) {
			throw new IllegalStateException(e.getMessage(), e);
		}
		return read(reader);
	}

	public static String readFromResource(String resource) throws IOException {
		InputStream in = null;
		try {
			in = Thread.currentThread().getContextClassLoader().getResourceAsStream(resource);
			if (in == null) {
				in = Utils.class.getResourceAsStream(resource);
			}

			if (in == null) {
				return null;
			}

			String text = Utils.read(in);
			return text;
		} finally {
			JdbcUtils.close(in);
		}
	}

	public static byte[] readByteArrayFromResource(String resource) throws IOException {
		InputStream in = null;
		try {
			in = Thread.currentThread().getContextClassLoader().getResourceAsStream(resource);
			if (in == null) {
				return null;
			}

			return readByteArray(in);
		} finally {
			JdbcUtils.close(in);
		}
	}

	public static byte[] readByteArray(InputStream input) throws IOException {
		ByteArrayOutputStream output = new ByteArrayOutputStream();
		copy(input, output);
		return output.toByteArray();
	}

	public static long copy(InputStream input, OutputStream output) throws IOException {
		final int EOF = -1;

		byte[] buffer = new byte[DEFAULT_BUFFER_SIZE];

		long count = 0;
		int n = 0;
		while (EOF != (n = input.read(buffer))) {
			output.write(buffer, 0, n);
			count += n;
		}
		return count;
	}

	public static String read(Reader reader) {
		try {

			StringWriter writer = new StringWriter();

			char[] buffer = new char[DEFAULT_BUFFER_SIZE];
			int n = 0;
			while (-1 != (n = reader.read(buffer))) {
				writer.write(buffer, 0, n);
			}

			return writer.toString();
		} catch (IOException ex) {
			throw new IllegalStateException("read error", ex);
		}
	}

	public static String read(Reader reader, int length) {
		try {
			char[] buffer = new char[length];

			int offset = 0;
			int rest = length;
			int len;
			while ((len = reader.read(buffer, offset, rest)) != -1) {
				rest -= len;
				offset += len;

				if (rest == 0) {
					break;
				}
			}

			return new String(buffer, 0, length - rest);
		} catch (IOException ex) {
			throw new IllegalStateException("read error", ex);
		}
	}

	public static String toString(java.util.Date date) {
		if (date == null) {
			return null;
		}
		SimpleDateFormat format = new SimpleDateFormat("yyyy-MM-dd HH:mm:ss");
		return format.format(date);
	}

	public static String getStackTrace(Throwable ex) {
		StringWriter buf = new StringWriter();
		ex.printStackTrace(new PrintWriter(buf));

		return buf.toString();
	}

	public static String toString(StackTraceElement[] stackTrace) {
		StringBuilder buf = new StringBuilder();
		for (StackTraceElement item : stackTrace) {
			buf.append(item.toString());
			buf.append("\n");
		}
		return buf.toString();
	}

	public static Boolean getBoolean(Properties properties, String key) {
		String property = properties.getProperty(key);
		if ("true".equals(property)) {
			return Boolean.TRUE;
		} else if ("false".equals(property)) {
			return Boolean.FALSE;
		}
		return null;
	}

	public static Boolean getBoolean(GenericServlet servlet, String key) {
		String property = servlet.getInitParameter(key);
		if ("true".equals(property)) {
			return Boolean.TRUE;
		} else if ("false".equals(property)) {
			return Boolean.FALSE;
		}
		return null;
	}

	public static Integer getInteger(Properties properties, String key) {
		String property = properties.getProperty(key);

		if (property == null) {
			return null;
		}
		try {
			return Integer.parseInt(property);
		} catch (NumberFormatException ex) {
			// skip
		}
		return null;
	}

	public static Long getLong(Properties properties, String key) {
		String property = properties.getProperty(key);

		if (property == null) {
			return null;
		}
		try {
			return Long.parseLong(property);
		} catch (NumberFormatException ex) {
			// skip
		}
		return null;
	}

	public static Class<?> loadClass(String className) {
		Class<?> clazz = null;

		if (className == null) {
			return null;
		}

		try {
			return Class.forName(className);
		} catch (ClassNotFoundException e) {
			// skip
		}

		ClassLoader ctxClassLoader = Thread.currentThread().getContextClassLoader();
		if (ctxClassLoader != null) {
			try {
				clazz = ctxClassLoader.loadClass(className);
			} catch (ClassNotFoundException e) {
				// skip
			}
		}

		return clazz;
	}

	private static Date startTime;

	public final static Date getStartTime() {
		if (startTime == null) {
			startTime = new Date(ManagementFactory.getRuntimeMXBean().getStartTime());
		}
		return startTime;
	}

	public static long murmurhash2_64(String text) {
		final byte[] bytes = text.getBytes();
		return murmurhash2_64(bytes, bytes.length, 0xe17a1465);
	}

	/**
	 * murmur hash 2.0, The murmur hash is a relatively fast hash function from
	 * http://murmurhash.googlepages.com/ for platforms with efficient multiplication.
	 * 
	 * @author Viliam Holub
	 */
	public static long murmurhash2_64(final byte[] data, int length, int seed) {
		final long m = 0xc6a4a7935bd1e995L;
		final int r = 47;

		long h = (seed & 0xffffffffl) ^ (length * m);

		int length8 = length / 8;

		for (int i = 0; i < length8; i++) {
			final int i8 = i * 8;
			long k = ((long) data[i8 + 0] & 0xff) //
					+ (((long) data[i8 + 1] & 0xff) << 8) //
					+ (((long) data[i8 + 2] & 0xff) << 16)//
					+ (((long) data[i8 + 3] & 0xff) << 24) //
					+ (((long) data[i8 + 4] & 0xff) << 32)//
					+ (((long) data[i8 + 5] & 0xff) << 40)//
					+ (((long) data[i8 + 6] & 0xff) << 48) //
					+ (((long) data[i8 + 7] & 0xff) << 56);

			k *= m;
			k ^= k >>> r;
			k *= m;

			h ^= k;
			h *= m;
		}

		switch (length % 8) {
		case 7:
			h ^= (long) (data[(length & ~7) + 6] & 0xff) << 48;
		case 6:
			h ^= (long) (data[(length & ~7) + 5] & 0xff) << 40;
		case 5:
			h ^= (long) (data[(length & ~7) + 4] & 0xff) << 32;
		case 4:
			h ^= (long) (data[(length & ~7) + 3] & 0xff) << 24;
		case 3:
			h ^= (long) (data[(length & ~7) + 2] & 0xff) << 16;
		case 2:
			h ^= (long) (data[(length & ~7) + 1] & 0xff) << 8;
		case 1:
			h ^= (long) (data[length & ~7] & 0xff);
			h *= m;
		}
		;

		h ^= h >>> r;
		h *= m;
		h ^= h >>> r;

		return h;
	}

	public static byte[] md5Bytes(String text) {
		MessageDigest msgDigest = null;

		try {
			msgDigest = MessageDigest.getInstance("MD5");
		} catch (NoSuchAlgorithmException e) {
			throw new IllegalStateException("System doesn't support MD5 algorithm.");
		}

		msgDigest.update(text.getBytes());

		byte[] bytes = msgDigest.digest();

		return bytes;
	}

	public static String md5(String text) {
		byte[] bytes = md5Bytes(text);
		return HexBin.encode(bytes, false);
	}

	public static void putLong(byte[] b, int off, long val) {
		b[off + 7] = (byte) (val >>> 0);
		b[off + 6] = (byte) (val >>> 8);
		b[off + 5] = (byte) (val >>> 16);
		b[off + 4] = (byte) (val >>> 24);
		b[off + 3] = (byte) (val >>> 32);
		b[off + 2] = (byte) (val >>> 40);
		b[off + 1] = (byte) (val >>> 48);
		b[off + 0] = (byte) (val >>> 56);
	}

}
